Pesticides & Wildlife-Tobacco

Dated 2/92
Placed on the Web 3/95 by the Department of Entomology, NCSU

Wildlife is an important part of a healthy rural environment.
This fact sheet is one of a series that describes how pesticides
can be managed to minimize harm to wildlife on our farms, in our
waters, and in our forests.

Wildlife is a valuable natural resource. Most farmers enjoy seeing
wildlife on their farm, and many benefit economically by leasing
hunting and fishing rights to sportsmen. In North Carolina, more
than $1.1 billion is spent annually by hunters and fishermen
alone.

Tobacco fields provide both food and cover for wildlife. For
example, quail and other birds nest in grassy strips alongside
tobacco fields. Farm wildlife such as these are often called "edge
species" because they live in noncrop areas such as hedgerows or
along the edges of fields. Wildlife that live in these areas find
food and grit in the adjacent crop fields. Pesticides applied to
the fields are therefore likely to affect wildlife. For example,
researchers tested quail that had been killed by hunters and found
that 60 percent of the quail had insecticides in their bodies.

Wildlife that are directly exposed to toxic pesticides can get sick
or die. In a 1978 study of quail living near fields that had been
sprayed with methyl parathion, 35 percent had enough insecticide in
their bodies to cause sickness or death. Birds made sick by
insecticides may neglect their young, abandon their nests, and
become more susceptible to predators and disease.

While direct poisoning from toxic pesticides is a concern, many
pesticides that are not highly toxic can still be harmful to
wildlife by reducing the food and cover that wildlife need in order
to survive. Insecticides reduce insect foods, and herbicides
decrease plant cover. Herbicide use can reduce gamebird
populations on farms by disrupting habitats that chicks use to find
insects and other foods. Similarly, pesticides can decrease the
number of aquatic foods necessary to the survival of ducklings.

Careful selection and use of pesticides, however, can lessen their
impact upon wildlife. This publication (1) describes how
pesticides used on tobacco fields can harm wildlife and (2)
describes how farmers can minimize adverse effects of pesticides on
wildlife.

Insecticides

Wildlife are exposed to insecticides when they eat granules or
residues on plants and in insects. For instance, quail chicks feed
on dead and dying insects following applications of insecticides.
Wildlife entering tobacco fields during or soon after an
insecticide has been sprayed may be exposed when the pesticide
contacts their skin and eyes or when they inhale the vapor.

Exposure to highly toxic insecticides (mainly organophosphate and
carbamate insecticides) can result in death of the animal.
Sublethal exposure may cause sickness. Birds made sick by
insecticides are more susceptible to predation, disease, and
exposure. Birds exposed to organophosphate insecticides have been
found to neglect their young or even abandon their nests.

Insecticides used on tobacco range from nontoxic to extremely toxic
to wildlife. Many soil-applied insecticides are especially
hazardous to wildlife; they include carbofuran (Furadan), aldicarb
(Temik), fenamiphos (Nemacur), disulfoton (Di-Syston), and ethoprop
(Mocap). All of these insecticides are extremely toxic to birds
and have caused wildlife deaths.

Tables 1 and 2 list insecticides recommended in the
North
Carolina Agricultural Chemicals Manualfor use on soybeans.
Table 1 rates insecticides according to their toxicities to
birds, mammals, and fish. The effects of insecticides on wildlife
and fish can be minimized by using the least toxic alternative.
Insecticides in Table 2 are rated low, moderate, or high based on
the hazard their use presents to wildlife (birds and
mammals). The hazard of an insecticide is based on its toxicity to
wildlife, the way it is used, and other characteristics, such as
its persistence in the environment. For example, methomyl
(Lannate) is acutely toxic to birds and mammals (Table 1).
However, because methomyl does not persist in the field, careful
use of this chemical presents only a moderate hazard to wildlife
(Table 2). Wildlife exposed to insecticides rated high may
die or become sick. Insecticides rated moderate may also
cause death or sickness, although death is unlikely. Insecticides
rated low are unlikely to harm wildlife directly.

yes indicates wildlife deaths due to use of the insecticide (active
ingredient) have been reported.no indicates wildlife deaths have not been reported when pesticide
is used according to label.

Granular Insecticides

Granular formulations are a real hazard to birds. Birds eat
granules exposed on the soil surface, mistaking the granules for
food or grit. Ingesting only a few granules of a toxic insecticide
can kill a small bird.

To reduce the danger to wildlife from granular insecticides:

use the least toxic insecticide that will control the insect
pest

fully incorporate granules into the soil

Disking spilled granules into the soil at row ends is
especially important since many birds feed on the edges of fields.
When soil incorporation is not possible, consider using a liquid
formulation following the guidelines in the next section.

The hazard to wildlife posed by some soil-applied systemic
insecticides may warrant forgoing their use. Before using soil-
applied systemic insecticides, consider their advantages and
disadvantages discussed in the "Insect Management" section of the
Tobacco Information handbooks (AG-376 and AG-178) published
by the North Carolina Cooperative Extension Service.

Foliar Insecticides

The hazards of foliar-applied insecticides to wildlife range from
low to high (see Table 1). Several insecticides are relatively
safe; they include Bacillus thuringiensis (Biobit, Dipel, or
Javelin), carbaryl (Sevin), malathion, and acephate (Orthene).
Other foliar insecticides, such as methomyl (Lannate), methidathion
(Supracide), and methyl parathion are highly toxic to wildlife.
Most foliar insecticides used on tobacco are short-lived in the
environment, so the hazard to wildlife is short-term.

To reduce hazard to wildlife from liquid formulations:

spray only when IPM thresholds are met

use the least toxic insecticide that will control the insect
pest

minimize drift of insecticide that will control the insect
pest

Drift can be minimized by using application equipment with low
drift characteristics, replacing inappropriate or worn nozzles,
using appropriate pressure and volume for the chosen nozzle, and
adding a drift control agent. Ultra-low-volume sprays are more
likely to cause drift than low-pressure sprays. Of course, avoid
spraying when the wind is blowing faster than 8 mph.

Nematicides

Several soil-incorporated granular insecticides are also used as
nematicide treatments and are highly toxic to wildlife; these
include fenamiphos (Nemacur), aldicarb (Temik), ethoprop (Mocap),
and carbofuran (Furadan). If these pesticides are used, it is very
important to incorporate the granules into the soil to reduce
wildlife hazard. Also, liquid formulations, rather than granular,
may reduce wildlife hazard. Chlorpyrifos (Lorsban) and oxamyl
(Vydate) are the least hazardous nematicide alternatives but are
not as effective as some others in controlling nematodes.

Some fumigants are less hazardous to wildlife than nonfumigants
because of their short duration of activity. These fumigants
include dichloropropene (Telone II) and methyl bromide with
chloropicrin (Brom-O-Sol).

Proper cultural practices, including crop rotation, stalk and root
destruction, and use of resistant tobacco varieties, help to reduce
the use of nematicides. For more information, see Extension
Service publication AG-187, Tobacco Information.

Fungicides

Fungicides used on tobacco are only slightly toxic to wildlife;
these include metalaxyl (Ridomil), ferbam (Carbamate), and mancozeb
(Dithane M-45). Their use does not present a hazard to wildlife.
However, mancozeb is highly toxic to fish.

Fungicide use can be reduced by controlling seedling diseases with
cultural practices such as proper rotation, timely planting, and
proper seed selection.

Herbicides

Most herbicides used on tobacco are only slightly toxic to wildlife
(although some are highly toxic to fish). However, herbicides can
destroy wildlife habitats and reduce the food and cover available
to wildlife. When habitats are reduced on a farm, there is a
tremendous effect on the wildlife populations there. Wildlife
populations decline when herbicides or mechanical methods are used
to maintain "clean" fencerows, ditch banks, and field borders.
These strip habitats provide wildlife valuable cover for
nesting, brood rearing, and escaping from predators.

Many species of wildlife, including quail and rabbits, benefit from
strip habitats. Where possible, consider maintaining these areas
in wildlife cover. Protect these areas from herbicides and mow
less frequently. Consider mowing filter strips and ditch banks
only once per year, preferably in early spring. In fields where
weeds have been a problem, prevention of weed seed production in
non-crop habitats may be accomplished by using selective herbicides
that allow grass cover to be maintained.

Ways to Reduce Pesticide Use

Reducing pesticide use is one of the best ways to protect fish and
wildlife resources. Using sound cultural practices reduces pest
problems and, therefore, results in lower pesticide use. Cultural
practices that decrease the need for pesticides include rotating
crops, selecting resistant varieties (when possible), planting and
harvesting at the proper time, and using integrated pest management
(IPM) techniques. IPM is a farming approach that employs
alternative methods of pest control, rather than relying solely on
agrichemicals. With IPM, pesticides are used only when the cost of
applying a pesticide is outweighed by the cost of pest damage to
the crop. This "threshold" must be reached before chemical pest
control is economically justified. In this way, IPM practices help
to reduce pesticide use and protect wildlife and the environment.
For further information on alternatives to pesticide use, see the
list of additional readings at the end of this publication.

Remember These Tips To Protect Fish and Wildlife Resources

Incorporate IPM practices into your tobacco production

Use proper cultural practices that help to reduce pesticide
use.

Use the pesticide least toxic to fish and wildlife to get the
job done.

Protect field borders and other noncrop habitats from
herbicides and insecticides.